A check the channel parameter settings, the signal type settings are consistent with the actual access signal types;
The B-channel module switch settings are with the call signal type is consistent;
C Check the signal wiring is correct, the signal cable is good contact;
D there is no problem in determining the above-mentioned re-calibration instrument (note the precision of the signal source must be higher than 0.1%) if the instrument calibration is not normal (no calibration), or calibration of measurement channels is still not normal, but normal, Come contact with manufacturers

A multimeter at the terminals used to measure the signal is normal;
B-channel module switching and signal checks whether the type is set correctly;
C Open the case, check whether the access channel signal cable good.

Check the meter display cable is connected properly.

A check meter 220V power supply terminal wiring is correct;
B checks whether the meter fuse fuse;
C screw after the screw under the instrument, will form the core out from the front to check the power board cable between the motherboard and fits well